EP2229538B1 - Fastening element and corresponding setting method - Google Patents

Abstract

The invention proposes a blind fastening element, which is constructed similarly to a screw. The fastening element thus has a head (1), which is disposed on one end of the shaft (3) and has a contact surface, which faces toward the shaft, for contact on the object to be fastened. On the opposite front end, the fastening element has a punch face (7), which runs approximately transversely to the longitudinal axis and is enclosed by a closed punch edge (8). The diameter of said punch face is less than the diameter of the shaft, for example, the diameter is in the range of approximately 70% to 30% of the diameter of the shaft. The shaft itself may be smooth on its exterior, if the fastening element is to be used as a blind rivet, or may have a thread (9), however, if the fastening element is to be fastened after the punch procedure by rotating.

Description

The invention relates to a fastener, in particular for the connection of components, with which a fastening can be carried out from a front without access to the back is required. Fasteners of this type may be, for example, blind rivets, nails or self-drilling screws.

There is already a nail known as a blind fastener ( DE 102006002238A1 ), which is driven at high speed without rotation through the non-pre-punched in the joint components so that the nail tip completely penetrates both components until the bottom of the nail head connects to the thrown up material. This nail may have a rib-like circumferential profiling or a thread for releasing the connection.

From the post-published WO 2009/024311 A2 Blind rivets are known for attaching objects to each other. The blind rivets are injected or punched axially into the articles and then deformed under the action of a force acting in the opposite direction to set the rivet.

From the DE 195 35 537 A1 a method for inserting a bolt element in a sheet metal part or in another, consisting of deformable material, plate-shaped member is known, wherein the bolt member has a head part and a shaft part. The bolt element is guided with its front end through the sheet metal part, using a setting head is used. The setting head cooperates with a die arranged on the side facing away from the setting head of the sheet metal part, whereby the bolt element is riveted in the region of its head part with the sheet metal element. In order now to attach an object to the sheet metal part of this is placed on the shaft part and a nut screwed onto the thread of the shaft part, whereby it is held on the sheet metal part.

From the US 2,703,419A1 is a tool with a punch tip and a self-tapping thread known. With the tool, a hole can be punched in a sheet metal part, wherein on the opposite side of the tool of the sheet metal part a die is arranged with a circular blind hole. If the tool is pressed further into the die after punching a hole in the sheet metal part, an annular portion is pressed around the punch hole against the inner wall of the blind hole in the die. Subsequently, a thread is cut by rotation of the tool in the annular portion which bears against the hole wall of the die. On In this way, a "nut" with internal thread from the annular portion is formed, which is formed integrally with the sheet metal part.

From the GB 1479600A a screw is known which has a ballistic tip, a shank and a screw head, wherein the shank is thread-free on the tip side and has a thread on the head side. The tip-side end of the screw can be shot by two superimposed sheets such that the thread-free portion is arranged in the resulting hole. Subsequently, the screw is screwed into the hole with another tool to connect the sheets together.

Blind rivets with ballistic tips are also known.

The invention is based on the object to provide a fastener that is simple and provides good attachment results under different conditions.

To solve this problem, the invention proposes a fastener with the features mentioned in claim 1. The invention also proposes a method for setting such a fastener with the features mentioned in claim 22.

While in the above-mentioned fastener ( DE 10 2006 002 238 A1 ) the hole is produced by strong deformation of the components with the resulting distortions, the hole is first formed by the fastening element according to the invention in that a part of the two components or at least one of the two components is punched out. This leads to a clearly clean hole edge.

The fastener according to the invention has a tool engagement formation on which a tool for performing the punching operation engages. This is usually a force acting in the longitudinal direction of the fastener tool that exerts a force on the fastener in the longitudinal direction by a jerky or sudden movement.

To carry out the fastening operation, a tool engagement formation is likewise provided which, if appropriate, can also be identical to the tool engagement formation for the punching process. But it can also be a different drive training, even if both processes a single tool can be provided.

In a further development of the invention it can be provided that the punched end of the fastening element has a transversely to the longitudinal axis extending end face, which is bounded by a substantially completely circumferential punching edge. As a result, a defined part of the material is punched out. With a complete punching edge, the part is completely removed after punching. But it is also conceivable and useful not to form the punching edge completely encircling, but to a small part of the circumference with a rounded contour Mistake. Then, although a part of the material is punched out, wherein the punched-out part remains connected to the starting material at a small part of the edge, so that when performing the fastening operation of this part does not fall off, but is bent away to the side.

According to the invention, the diameter of said face is smaller than the diameter of the stem, and may for example preferably be in a range of about 30% to 70%, preferably 40% to 60% of the diameter of the stem.

The end face is smaller in diameter than the diameter of the shaft, thus according to the invention there is a transitional region between the two diameters which begins behind the end face. Here it can now be provided that the punching end of the fastening element extends cylindrically behind the end face. Cylindrical means that the cross-sectional size does not change, not even the cross-sectional shape. The cross-sectional shape does not need to be a circular shape, nor does the face itself need to be a circular area, but the circular area or at least an approximate circular area is considered preferable. Also possible is a polygon shape.

Instead of a cylindrically extending portion may also be provided according to the invention that behind the end face an initially undercut portion is present, where therefore the cross-sectional size initially reduced until it then increases continuously again to the diameter of the shaft.

It is also possible that the transition between the punched end and the shaft is at least partially conical. This conicity applies both when behind the end face a cylindrical section is present, as well as when there is an undercut.

Instead of a conical transition, the transition may be at least partially concave. In the case of a direct transition directly into the shaft itself, there may also be a slight convex curvature in the manner of a rounded transition.

It has already been mentioned that the end face present at the punching end of the fastening element extends transversely to the longitudinal direction of the fastening element or transversely to the axis of the fastening element. This is to express that a deviation from a plane perpendicular to the longitudinal axis should also be included.

More specifically, it can be provided that the front end face lies in a plane. This plane can both run exactly perpendicular to the longitudinal axis of the fastener, as well as slightly inclined thereto. The slight deviation from the vertical has the consequence that the punching process is not carried out at all points of the punching edge exactly at the same time, which may allow a cleaner cut. Above all, this promotes the cutting force profile.

The end face does not have to lie in one plane, it can easily deviate from this plane, for example, have two flat parts extending at an angle or even curved.

It has already been mentioned at the outset that the blind fastening element has a tool engagement formation for carrying out the punching process and a tool engagement formation for carrying out the fastening process following the punching process. Under certain circumstances, a single tool may be provided for both processes, for example one bit.

The attachment process is a turn. While the punching process is always a straight-line process running in the longitudinal direction of the fastening element, the fastening process is therefore a process in a different direction. Accordingly, the fastener on a Werkzeugangriffsausbildung, with which the fastener can be rotated. It may be the usual Schraubenantriebsbildungen in the form of protrusions or depressions.

In development of the invention can be provided that the shaft is at least partially smooth and cylindrical. This is especially the case when the attachment process is done by hitting or pulling.

It was mentioned in the beginning that the cross section of the punched end can be circular, but can also deviate from the circular shape. The invention proposes that the shank of the fastening element can at least partially have a circular cross-section.

However, it is also possible and is proposed by the invention that the shaft has at least partially deviating from the circular cross section, for example the shape of a polygon with strongly rounded corners, which is also known by the term trilobular in an approximated triangular shape.

According to the invention, it can be provided that the head of the fastening element, the shaft and the punched end form an integral component.

But it is also possible that the punching end is a separate from the shaft and the head associated with this component. This is particularly useful if you want to use for some reasons for the punching another or a different treated material.

The tool engagement formation for performing the punching operation is preferably a transverse to the axis of the fastener surface of the head of the fastener.

The head of the fastener may be a head, as it is known in screws, so for example, a hexagonal head with a flat bottom, the one Forms contact surface. But even a countersunk head is possible, which can then be sunk when screwing.

The invention also proposes a method with the features of the independent method claim. The fastener is used so that with its punching end by a sudden feed a hole is punched in the objects to be joined, that this hole is extended by a further advance of the fastener that the feed is terminated when the thread of the shaft in the hole passes, and then that the fastener is attached to the plant of his head with its underside. In this case, the further feed during screwing is determined only by the fastening operation, for example, the screwing.

In particular, it may be provided that the sudden feed is adjusted such that the feed ends when the threaded portion reaches the hole.

It can also be provided that the screwing already begins during the linear feed, so that the two movements overlap in time.

If the head of the fastening element is a countersunk head, the screwing-in process can also be carried out until the upper side of the fastening head is flush with the surface of the upper of the two objects to be joined.

Figur 1

die Seitenansicht eines ersten Befestigungselements nach der Erfindung;

Figur 2

in vergrößertem Maßstab das Stanzende eines zweiten Befestigungselements;

Figur 3

eine Seitenansicht des Stanzendes mit einer konvex gekrümmten Stirnfläche;

Figur 4

die Seitenansicht des Stanzendes mit einer konkav gekrümmten Stirnfläche;

Figur 5

die Seitenansicht des Stanzendes mit einer schräg verlaufenden Stirnfläche;

Figur 6

die Stirnfläche mit einer fast vollständig geschlossenen Stanzkante;

Figur 7

eine der Figur 2 entsprechende Darstellung bei einer weiteren Ausführungsform;

Figur 8

eine der Figur 7 entsprechende Darstellung bei einer nochmals weiteren Ausführungsform;

Figur 9

das vordere Stanzende in einer abgeänderten Ausführungsform.

Further features, details and advantages of the invention will become apparent from the claims and the abstract, the wording of which is incorporated by reference into the content of the description, the following description of preferred embodiments of the invention and with reference to the drawing. Hereby show:

FIG. 1

the side view of a first fastener according to the invention;

FIG. 2

on an enlarged scale, the punched end of a second fastener;

FIG. 3

a side view of the punched end with a convexly curved end face;

FIG. 4

the side view of the punched end with a concave curved end face;

FIG. 5

the side view of the punched end with a sloping end face;

FIG. 6

the end face with an almost completely closed punching edge;

FIG. 7

one of the FIG. 2 corresponding representation in a further embodiment;

FIG. 8

one of the FIG. 7 corresponding representation in yet another embodiment;

FIG. 9

the front punching end in a modified embodiment.

FIG. 1 shows in a simplified side view of a first fastener having a head 1 at one end. This head 1 contains a lying in a plane bottom 2, to which a shaft 3 is connected. On the underside 2 opposite top 4 of the head, a flat surface is formed. Starting from this flat surface extending into the head 1 in a dashed lines indicated recess 5, which has the shape of a conventional screw drive training. The upper side 4 of the head can also have a different shape, for example, be convexly curved.

In the region of the end facing away from the head 1 of the fastening element, the screw shank 3 transitions over a concavely curved section 6 into a front end face 7. This end face 7 has a peripheral edge 8, which is formed as a punching edge. This means that it is so sharp-edged that it can punch the material when striking this punched end of the fastener. Sharp-edgedness therefore depends on the type of material to be punched and the impact movement.

Starting from the head 1 of the fastening element, the shaft 3 has a thread 9, which is indicated. It ends just before the cylindrical part of the shaft3.

This fastener is intended to produce by punching a hole in the material to be fastened opposite. The punching is done by a sudden movement, which is transmitted by a tool on the fastener. For this purpose, the top 4 of the head 1. This top 4 thus forms an attack training for a tool that should perform the punching process.

The actual attachment in the material against which the attachment is to be made, then done by rotation of the fastener, in which case the fastener is screwed by means of the thread 9. In order to be able to exert a rotational movement for the screwing movement on the fastening element, the recess 5 is provided in the illustrated embodiment, which thus forms the attack training for a tool for performing the fastening operation. Of course, it is also possible that the head of the fastening element is designed as a polygonal head, in particular as a hexagonal head.

The front flat end face 7 extends in the in FIG. 1 illustrated embodiment in a plane which is perpendicular to the longitudinal axis of the fastener.

Directly behind the end face 7 and thus also directly behind the punching edge 8, the punched end 10 initially extends in a cylindrical section 6a or with a slight undercut, from where the contour then runs concavely curved up to the shaft 3.

FIG. 2 only shows the front punching end 10 in a slightly modified embodiment. Again, the end face 7 extends with the punching edge 8 in a plane which is perpendicular to the longitudinal axis of the fastener. Immediately behind the end face 7 reduces the diameter and thus the cross section in a first region 6b. The transition between the end face 7 and the shaft 3 thus takes place in a concave shape with an undercut behind the end face. 7

Both in the embodiment according to FIG. 1 as well as in the embodiment according to FIG. 2 the end face 7 is a flat surface which is perpendicular to the longitudinal axis of the fastener. In a modification shows the FIG. 3 the punching end of another embodiment in which the end face 17 is convexly curved, said end face 17 is still approximately perpendicular to the longitudinal axis.

A correspondingly reversed curved end face 27 shows the FIG. 4 ,

The FIG. 5 now shows a modification in such a way that the front end surface 37, although again formed as flat surfaces, as in the embodiment according to FIG. 1 and FIG. 2 , but now this flat surface but slightly inclined to the nature of the face of the FIGS. 1 and 2 is arranged. Here, the punching process begins in FIG. 5 on the left side, so that the punching edge does not perform the punching at all places at the same time.

FIG. 6 shows the end face 7 with the punching edge 8. The punching edge 8 extends along a substantially closed line and is interrupted only at one point 11 in such a way that there the transition between the lateral surface and the end surface is rounded. This is to ensure that the part punched out during the stamping process hangs on the material at a point which is so narrow that it is bent over but does not tear off.

While in the previous embodiments, the transition region between the punched end and the cylindrical shaft 3 is formed smooth, the show FIGS. 7 and 8 Embodiments in which the transition region 41 between the shaft 3 and the punched end 50 is also provided with a thread 49. With other varieties, the thread goes from the shaft 3 to the end of the transition region 41, where the thread 49 ends or begins, as the case may be. Thus, as soon as the thread 49 reaches the hole, an enlargement of the punched hole by the screwing operation takes place at this point.

The transition region 41 may comprise any of the basic shapes described and illustrated so far with reference to FIGS FIGS. 1 to 4 were presented. The same is true for the punching end 50 itself and its face 7. At the in FIG. 7 illustrated embodiments, the contour of the transition region 41 is convex.

FIG. 8 shows an embodiment where the transition region 42 is tapered. In the FIG. 8 illustrated embodiment differs from the after FIG. 7 among other things also in that a scraping groove 43 is formed over the thread, which runs slightly obliquely with respect to the longitudinal axis of the fastening element. This can be achieved that also takes place a cutting process to form the thread.

FIG. 9 shows yet another embodiment of a punched end 60. Immediately to the end face 7 then a kind of plate is formed, behind which the diameter of the punched end is reduced stepwise. So here is a step-like undercut formed.

Fasteners, as in FIGS. 7 and 8 can be combined with any end faces and with any fastener heads.

The fastener may be used to attach different materials to each other, for example, sheet metal on sheet metal, from sheet metal to wood and sheet metal on plastic. It can be provided to use different thread forms for a wide variety of applications.

In the illustrated embodiments, the screw thread on the shaft extends to the bottom of the screw head or a countersunk head. This is not required. It may also be sufficient if the thread extends, for example, only over half of the shaft. The configuration in which the thread does not extend to the underside of the head is particularly advantageous if it is intended to pull the metal sheet present closer to the head of the fastening element to the base.

Claims (26)

1. A blind fastening element for fastening objects to each other, having a shaft (3), a head (1) which is formed at one end of the shaft (3) and has a contact face on its underside (2) facing the shaft (3), a self-cutting thread (9) on the shaft (3) for connecting the said objects to each other, a punch end (10, 50, 60) formed at the opposite front end of the shaft (3) for punching a hole and a transition region between the punch end and the shaft for widening the hole, a tool engagement formation for carrying out a punching process, for punching out a defined portion of the material, and having a tool engagement formation for carrying out a turning process, in particular a screwdriving formation.
2. The blind fastening element according to claim 1, in which the punch end (10, 50, 60) has a transverse end face (7, 17, 27, 37) which is delimited by an essentially complete punch edge (8).
3. The blind fastening element according to claim 2, in which the diameter of the end face (7, 17, 27, 37) is between approximately 30% and 70%, preferably between approximately 60% and approximately 40% of the diameter of the shaft (3).
4. The blind fastening element according to one of the preceding claims, in which the punch end (10, 50, 60) has a cylindrical section (6a) behind the end face (7, 17, 27, 37).
5. The blind fastening element according to one of claims 1 to 3, in which the punch end (10, 50, 60) has an undercut section (6b) behind the end face (7, 17, 27, 37).
6. The blind fastening element according to one of the preceding claims, in which the transition between the end face of the punch end and the shaft (3) is at least partially conical.
7. The blind fastening element according to one of the preceding claims, in which the transition between the end face of the punch end and the shaft (3) is at least partially concave.
8. The blind fastening element according to one of the preceding claims, in which the front end face (7, 37) lies in one plane.
9. The blind fastening element according to one of the preceding claims, in which the front end face (37) lies in a plane which runs slightly obliquely to a transverse plane.
10. The blind fastening element according to one of claims 1 to 7, in which the punch edge (8) deviates slightly from a plane.
11. The blind fastening element according to one of the preceding claims, in which the shaft (3) is at least partially smooth and cylindrical.
12. The blind fastening element according to one of the preceding claims, in which the thread extends over the transition region between the punch end and the shaft (3).
13. The blind fastening element according to claim 12, having at least one tapping point (43).
14. The blind fastening element according to one of the preceding claims, in which the shaft (3) has at least partially a circular cross section.
15. The blind fastening element according to one of the preceding claims, in which the shaft (3) has at least partially a trilobular cross section.
16. The blind fastening element according to one of the preceding claims, in which the shaft, the head and the punch end form a single-piece component.
17. The blind fastening element according to one of claims 1 to 15, in which the punch end (30, 40) is a component which is separated from the shaft (3) and connected to the latter.
18. The blind fastening element according to one of the preceding claims, in which the tool engagement formation for carrying out the punching process is a surface (4) of the head (1) of the fastening element which runs transversely to the axis of the fastening element.
19. The blind fastening element according to one of the preceding claims, in which the head (1) has a flat contact shoulder on its underside (2).
20. The blind fastening element according to one of claims 1 to 18, in which the head of the fastening element is a countersunk head.
21. The blind fastening element according to one of claims 1 to 19, in which the head of the fastening element is a polygonal head, in particular a hexagonal head.
22. A method for setting a fastening element according to one of the preceding claims, having the following method steps:

    provision of objects to be fastened to each other,

    provision of a fastening element according to one of the preceding claims,

    a hole is punched in the objects (23, 24) to be connected by means of a sudden advance with the punch end (10, 50, 60) of the fastening element, in order to punch out a defined portion of the material,

    the hole is widened by a further advance of the fastening element,

    the advance is ended as soon as the thread (9) of the shaft (3) arrives at or into the hole,

    the fastening element is screwed in, forming a thread, in order to connect the objects with each other.
23. The method according to claim 22, in which the sudden advance is configured in such a manner that when the threaded section (9) reaches the hole, the advance ends.
24. The method according to claim 22 or 23, in which the processes of the sudden advance and the screwing overlap in time.
25. The method according to one of claims 22 to 24, in which the fastening element is screwed in until the head (1) thereof makes contact and/or until a countersink is formed by a countersunk head of the fastening element.
26. The method according to claim 24 or 25, in which the fastening element is set in rotation already at the start of the sudden advance.

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